1. Technical Field
The present invention relates to a projector which includes a light source, a light modulating device for forming a light image by modulating a light beam projected from the light source in response to image information, a projection lens for projecting the formed light image, and a chassis housing the light source, the light modulating device, and the projection lens therein.
2. Related Art
In the past, there was widely used a projector which includes a light source, a light modulating device for forming a light image by modulating a light beam projected from the light source in response to image information, and a projection lens for projecting the formed light image. Such a projector can extensively project the light image formed by the light modulating device on a screen, etc. through the projection lens.
Herein, the projection lens may be easily damaged. Accordingly, it is necessary to protect the projection lens when the projector is not used. There is widely used a projector provided in a chassis housing the device body therein so as to slidably move a lens cover for protecting the projection lens (for example, see JP-A-2001-249402). The projection lens is covered and protected by sliding the lens cover in one direction along the chassis in the projector disclosed in JP-A-2001-249402. In addition, the projection lens is exposed by sliding the lens cover in another direction. Therefore, it becomes possible to project the light beam as the light image through the projection lens. Two switches are provided in the device body of the lens cover and the opened/closed state of the lens cover is detected by the switches.
Specifically, the two switches are formed of detector switches. One switch is provided adjacent to a projection lens and the other switch is provided away from the projection lens rather than the one switch in the slide direction of the lens cover. It is possible to detect an opened state, a standby state (state when the lens cover covers a part of the projection lens), and a closed state of the lens cover by detecting the on/off state of the switches. In the projector disclosed in JP-A-2001-249402, an emitted light amount of a light source and the number of rotations of a cooling fan are controlled depending on the opened/closed state of the lens cover.
However, in a projector disclosed in JP-A-2001-249402, when a lens cover is slightly shifted from a closed state, a switch disposed away from a projection lens is turned off by a slide movement of the lens cover. Accordingly, even when the projection lens is not covered with the lens cover, there is a problem that it is determined that the lens cover is in a standby state. Accordingly, since the amount of light emitted from the light source decreases and the number of rotations of the cooling fan decreases due to the slight movement of the lens cover, the operation of a projector is not stabilized. Assumed that a switch for detecting the opened/closed state of the lens cover is formed of a pressing switch such as a detector switch, the on/off state of the switch is mechanically switched with the slide movement of the lens cover. Accordingly, the switch state is not recovered, thereby lowering the reliability at the time of detecting the opened/closed state of the lens cover.